1. Field of the Invention
The present invention relates generally to an antenna, and more particularly to a dual-band dipole antenna. The instant application relates to a contemporarily filed application having the same title, the common applicants and the same assignee with the invention.
2. Description of the Prior Art
In recent years, Wireless Local Area Network (WLAN) products under IEEE 802.11a/b/g and Bluetooth standards, such as WLAN cards for computers are gaining popularity in wireless communication market. Wherein, IEEE 802.11b/g and Bluetooth standard is suitable for working at 2.4–2.5 GHz frequency band, while IEEE 802.11a standard is suitable for working at 5–6 GHz frequency band. Many of said WLAN products want to be use under both IEEE 802.11a and IEEE 802.11b/g/Bluetooth standards benefit from dual-band antennas.
For achieving dual-band effect, a dual-band dipole antenna is one of the most mature dual-band antennas in both design and manufacture.
A conventional multi-band dipole antenna is disclosed in U.S. Pat. No. 6,421,024 B1. Said conventional multi-band dipole antenna comprises at least a first antenna having two lower dipole halves, a second antenna having two higher dipole halves and a coaxial cable feeding the first and the second antenna. Each of the dipole halves is formed from an electrically conductive cylindrical tube. Wherein, each upper lower dipole half and corresponding upper higher dipole half are interconnected at a closed top plate. The other lower dipole half and the other higher dipole half are interconnected at a closed bottom plate. The lower dipole halves are jointly operated at a lower frequency band range, while the higher dipole halves are jointly operated at a higher frequency band range. However, the cylindrical tube configuration seems to be complex in structure and must result in a higher cost. Furthermore, the feeder point of the antenna is arranged on the top plate, which is adjacent to the corresponding bottom plate with only a small space remained therebetween. When manufacturing, an inner conductor of the coaxial cable is welded on the bottom plate using a brand iron. The brand iron is so hard to be inserted into the small space that the welding is difficult to be finished.
Hence, in this art, a dual-band dipole antenna with simple structure and low cost, and easy to be manufactured to overcome the above-mentioned disadvantages of the prior art will be described in detail in the following embodiments.